Magnetic recording heads used in disk drives typically incorporate air bearing sliders that float a head over the surface of a rotating magnetic disk. The head reads and writes data on the disk. A gimbal assembly with an actuator arm supports the slider, enabling reciprocation of the head across the disk surface. During reciprocation, the actuator arm precisely positions the head over individual data tracks of the disk.
Rotation of the disk generates airflow along the disk surface. The airflow lifts slider and head to a flying height above the disk. Close spacing between the head and the disk surface allows short wavelength, height frequency signals to be recorded, thereby affording high density, high storage capacity recording. During operation of the disk drive, it is desirable to maintain the head at a substantially constant flying height and a tightly controlled pitch relative to the disk surface.
Known air-bearing sliders include side pads or rails and some sliders include a center pad located at the trailing edge of the air bearing slider to reduce variations in slider pitch associated with rapid movement of the head actuator arm. The pads define air-bearing surfaces that build pressure to lift the air bearing slider.
The head actuator arm reciprocates along an arc, from an inside diameter of the magnetic disk to an outside diameter of the disk as the disk spins. The angle of the head arm, and thus, the angle of the air-bearing slider relative to the disk changes during head arm reciprocation. Ideally, the air-bearing slider is configured to accommodate these angular changes. However, current designs may cause the flying height to change when the angle of the head arm changes.
During rotation of the magnetic disk, the outside diameter of the disk moves over a larger distance than the inside diameter of the disk. Hence, the linear velocity of the disk relative to the air bearing surface varies, being lesser near the inside of the disk and greater near the outside of the disk. Such variations in disk linear velocity result in changes in air bearing lift forces, which may affect the flying height of the air bearing slider. Current air bearing slider designs may not achieve a constant flying height because of the changes in linear velocity of various portions of the disk. During operation of a disk drive, when a magnetic disk begins to rotate, the leading edge of the air-bearing surface pitches.